The present invention relates to friction material and in particular to a friction material made from volcanic black rock and used in brake and clutch systems and similar applications.
Known vehicles require means for reducing linear velocity and momentum and means for reducing angular velocity and momentum of rotating members carrying the vehicles. Mechanical friction brakes are commonly used for such purposes and known brakes are suitable for typical vehicles operated at moderate speeds and loads in flat terrain. Such friction brakes work by converting kinetic energy into heat energy, and the greater the speed or mass of the moving vehicle, the greater the amount of heat generated to slow or stop the vehicle. The friction is generally created by forcing a friction material against a rotating surface. When vehicles are operated at high speeds with frequent braking, with heavy cargo creating greater linear momentum, or on long down hill stretches of road, the friction material may overheat and either fail or fade. Such loss of braking creates a severe risk of accidents. Although disk brakes have greatly improved braking performance over older drum brakes, there remains a need to further improve friction material used in vehicle brakes for both commercial and racing applications.
Many applications also require coupling and decoupling rotating members initially rotating at different angular speeds. The different angular speeds of the rotating members generally must first be synchronized before final coupling is achieved, and in the case of a manual transmission vehicle, motion is initiated from a stop by briefly slipping a clutch before fully engaging. In known vehicles, the clutch couples an engine flywheel to a transmission input shaft. Commonly, a clutch pressure plate is rotationally fixed to the flywheel and a clutch disk(s) with friction material on two opposite sides is sandwiched between the pressure plate and the flywheel. The clutch disk includes an inside spline which engages the transmission input shaft. The pressure plate includes an axially moving plate and spring(s) which push the plate against the clutch disk. The amount of torque transmittable through the clutch is proportional to the force applied on the plate by the springs, and in some instances, by weights and effects of centrifugal force. When the vehicle makes a standing start, the clutch slippage creates heat which may damage the friction material and result in continuous clutch slippage while driving. Because of the clutch slippage issue, clutches in high performance applications remain a weak link between the engine and transmission and a need remains for an improved friction material.